This invention applies to articulated vehicles such as semi-trucks, railroad cars and other vehicles where different sections of the vehicle are attached to one another by means of an articulated linkage of the type of a hitch assembly, and the invention relates to a Ride Control System (RCS) for restoring stability to the trailed part(s) of the vehicle when unwanted erratic jackknifing occurs at cruising speed. Throughout the following description of the invention, an on-highway semi truck will be referred to as a typical application for RCS.
A semi truck is commonly configured in such a way that when the vehicle makes a turn, its trailer(s) must pivot around the hitch assembly that connects the trailer to the tractor in order for the vehicle, as a whole, to complete the turn. The trailer behavior, and in particular the angle that it forms with its tractor vehicle, is referred to as jackknifing. Jackknifing is inherent of the mechanical configuration that allows the trailer to be attached to the tractor in a less rigid way. Under some driving conditions where the vehicle is moving straight ahead and the driver is not engaged in a steering maneuver, erratic jackknifing can occur and cause the trailer to wander laterally with respect to the vehicle. If this type of vacillating movement persists long enough and achieves a critical frequency, the trailer could be thrown off the hitch assembly and roll over. The damage caused by a rolled over trailer can be significant and cost lives.
Being able to detect and to counteract such erratic jackknifing is a difficult skill to acquire for an average truck driver. In this invention an electronically controlled and mechanically operated RCS is presented to assist the drivers of semi-trucks (the preferred application) and other articulated vehicles by providing means for detecting and counteracting unwanted erratic jackknifing. The system continuously monitors several inputs, including the driver's intention, the road conditions, and the trailer position. It is the combination of these inputs that allows the RCS to determine the probability of a roll-over due to erratic jackknifing. In the event of high probability of a roll-over the system would apply brakes to selected trailer wheels in such a way that the trailer can be dragged on one side or another and be forced to line up with the tractor truck.